Chemicals, plastics and rubber industries

Two modes of transformation of amorphous calcium carbonate films in air

Article Abstract:

Large area amorphous calcium carbonate (ACC) films in air are shown to be transformed into crystalline calcium carbonate (CaCO(sub 3)) films through two modes, dissolution-recrystallization and solid-solid phase transition, depending on the relative humidity of air and temperature. It was also found that, under high humidity, ACC tends to dissolve and recrystallize while at high temperatures, it is transformed into crystalline form through a solid-solid phase and all these results show that calcium carbonate can be obtained by this method.

Roles of charge polarization and steric hindrance in determining the chemical reactivity of surface Si-H and Si-Si bonds at H-terminated Si(100) and -(111)

Article Abstract:

The FTIR and XPS spectra and flat-band potentials measurement of the reactions of surface Si-H and Si-Si bonds at H-terminated Si(100) and -(111) are performed. The results indicate charge polarization and steric hindrance in the surface bond are important factors in determining the reactivity of these bonds in concentrated hydrogen halide solutions.